diff --git a/pkg/sql/rowexec/project_set.go b/pkg/sql/rowexec/project_set.go
index 5f7a70273fd0..ca37d0ebd5cd 100644
--- a/pkg/sql/rowexec/project_set.go
+++ b/pkg/sql/rowexec/project_set.go
@@ -144,6 +144,13 @@ func (ps *projectSetProcessor) nextInputRow() (
 		if fn := ps.funcs[i]; fn != nil {
 			// A set-generating function. Prepare its ValueGenerator.
 
+			// First, make sure to close its ValueGenerator from the previous
+			// input row (if it exists).
+			if ps.gens[i] != nil {
+				ps.gens[i].Close(ps.Ctx)
+				ps.gens[i] = nil
+			}
+
 			// Set ExprHelper.row so that we can use it as an IndexedVarContainer.
 			ps.exprHelpers[i].Row = row